1. Field of the Invention
The present invention relates to a pneumatic tire suitable for winter use. More particularly, the present invention relates to a pneumatic tire having improved in on-ice performance and on-snow performance.
2. Background Information
A pneumatic tire for winter use such as a studless tire conventionally has a particular configuration. Specifically, multiple longitudinal grooves extending in a tire circumferential direction and multiple lateral grooves extending in a tire width direction are provided in a tread portion, and these longitudinal and lateral grooves define multiple blocks. Multiple sipes extending in the tire width direction are provided in each of the blocks as described, for example, in Japanese patent application Kokai publication No. 2009-96220.
Such a pneumatic tire for winter use typically requires both on-ice performance and on-snow performance. Generally, when the on-ice performance is to be improved, the number of sipes to be provided in each block is increased to increase the edge effect exhibited by the sipes. However, providing many sipes in each block reduces the block stiffness, and thus, reduces the driving stability on snow. In some cases, even the on-ice performance is reduced due to collapsing of the blocks. Accordingly, it is difficult to improve both the on-ice performance and the on-snow performance at the same time.